Blockchain Demo - Visual demonstration of blockchain technology
Blockbutler - Real-time transaction notifications for the blockchain
Crypti - A minimal cross-platform Bitcoin price widget
Notif.me SDK - A Node.js lib to send all your transactional notifications
Explain Me Please - Complex topics explained for your level and background
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.